Submersible pumping systems are often deployed into wells to recover petroleum fluids from subterranean reservoirs. Typically, a submersible pumping system includes a number of components, including an electric motor coupled to one or more pump assemblies. Production tubing is connected to the pump assemblies to deliver the petroleum fluids from a production stream in the subterranean reservoir to a storage facility on the surface.
Production streams usually contain a combination of liquids and gases, and excessive amounts of gases in the production stream can cause the pump to malfunction or operate inefficiently. In progressive cavity pumps, gas pockets occupy space in the pump that could otherwise be occupied by desirable liquids, thereby lowering the efficiency of the pump. Most pumps work best with a gas concentration in the production stream of less than twenty five percent.
Rotary gas separators have been used to remove gas from production streams before entry into the pump. Rotary gas separators take advantage of the difference in specific gravities of gas and liquids by using centrifugal force to separate the gas and liquid components. Rotary mechanisms such as spinning chambers force the liquids to the outside radius of the rotary separator and the gases remain near the inside radius of the rotary separator because liquids are heavier than gases.
The radial positions of the liquids and gases after centrifugal separation are disadvantageously located for the desired venting of the gases to the wellbore and the axial pumping of the liquids. To solve this problem, rotary separators often employ crossover mechanisms that transfer the liquids to the center of the separator for entry into the pump and transfer the gases to the outer radius of the separator for venting away from the pump. These mechanisms include passages that route the gases and liquids to the desired location for venting into the wellbore or for pumping to the surface. The rotary and crossover mechanisms add complexity and cost to the separators, and can result in costly downtime for the submersible pumping system when repairs are needed.
It would therefore be desirable to separate liquids and gases in a production stream without the use of complex mechanisms that increase manufacturing and maintenance costs. It is to these and other deficiencies in the prior art that the present invention is directed.